In modern drive systems, such as power trains for motorized vehicles, torque vectoring and active-yaw-systems becomes more and more prominent. With active-yaw-systems or torque-vectoring systems, torque is selectively unevenly distributed to the left and right wheel of a vehicle axle. In order to manipulate angular yaw acceleration of the vehicle, electronically controlled active-yaw or torque-vectoring systems therefore provide a kind of steering effect that may provide improved vehicle agility and stability.
In effect, active-yaw systems or torque-vectoring systems improve the vehicle's stability against understeering or oversteering. Hence, an arising yaw momentum can be counterbalanced by precisely dosed longitudinal forces on front and rear axle. In this way, a fully adjustable optimized lateral driving dynamics can be achieved. Active-yaw systems can further improve the turn-in response speed and damping as result of the driver's steering inputs, resulting in a more responsive and easier handled vehicle.
Generally, active-yaw-systems and torque-vectoring systems make use of branching off a certain amount of torque from a propulsion drive mechanism. Available systems are changing the torque bias between the left and right wheels of an axle. These mechanisms slow down the inner wheel and the outer wheel is speeded up. This means that, regardless of the input torque, there will be a torque difference proportional to the speed difference imposed between the wheels. Typical existing solutions include transmission gears between a left and a right wheel of an axle, wherein respective drive shafts of the transmission gears are to be coupled with the propulsion drive or with respective wheels by means of numerous clutches.
A limitation of systems with fixed speed difference ratio operated via a slipping clutch is that the biasing depends on the cornering radius and the amount of clutch locking. Of course, slipping of the clutch will result in clutch wear and energy losses which limit the duration and amount of engagements. Also, the speed difference transmissions have drag losses even when not used. Finally, if the free-rolling speed difference due to a tight cornering radius is equal or larger than the speed ratio of the gearing, then no vectoring is possible.
Almost any active-yaw-system or torque-vectoring-system makes use of such a torque branching off, wherein the torque between the two outputs of the differential is biased.
Such a solution is for example illustrated in DE 10 2005 040 253 B3. It is characterized by two clutches, whose outer parts are axially tensed by means of a bridging element.
Such active-yaw or torque-vectoring systems are generally quite elaborate in construction and cost-intensive in production.
Recent developments suggest the implementation of an additional, auxiliary electric motor for providing an offset torque to be superimposed to the various wheel axles that are subject to active-yaw or torque-vectoring. Since active-yaw or torque-vectoring in typical applications is only applied occasionally, the auxiliary motor is idle during residual time intervals during which the auxiliary motor is not required.
It is therefore at least one object to provide a drive mechanism for transmitting torque to at least a first and a second output member, wherein a drive member, such as an auxiliary motor can be used in a more efficient and universal way. Moreover, it is at least a further object, to provide a torque transmitting and distributing drive mechanism, that comprises a simple internal structure, allowing for an easy and cost-efficient manufacturing.